linux-kernel - Re: [tip:x86/asmlinkage] x86, asmlinkage: Make kprobes code visible and fix assembler code

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Date:	Wed, 07 Aug 2013 12:55:38 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org,
	anil.s.keshavamurthy@...el.com, davem@...emloft.net,
	ananth@...ibm.com, masami.hiramatsu.pt@...achi.com,
	ak@...ux.intel.com, tglx@...utronix.de, hpa@...ux.intel.com
Cc:	tip-bot for Andi Kleen <tipbot@...or.com>,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/asmlinkage] x86, asmlinkage: Make kprobes code visible
 and fix assembler code

(2013/08/07 6:43), tip-bot for Andi Kleen wrote:
> Commit-ID:  04bb591ca74fb8ea06d5ab7fadfb7bf5b11fb28e
> Gitweb:     http://git.kernel.org/tip/04bb591ca74fb8ea06d5ab7fadfb7bf5b11fb28e
> Author:     Andi Kleen <ak@...ux.intel.com>
> AuthorDate: Mon, 5 Aug 2013 15:02:41 -0700
> Committer:  H. Peter Anvin <hpa@...ux.intel.com>
> CommitDate: Tue, 6 Aug 2013 14:19:48 -0700
> 
> x86, asmlinkage: Make kprobes code visible and fix assembler code
> 
> - Make all the external assembler template symbols __visible
> - Move the templates inline assembler code into a top level
>   assembler statement, not inside a function. This avoids it being
>   optimized away or cloned.

Oh, I didn't know that I can use asm() at top level. Thanks!

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>

> Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> Link: http://lkml.kernel.org/r/1375740170-7446-8-git-send-email-andi@firstfloor.org
> Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
> ---
>  arch/x86/include/asm/kprobes.h | 10 +++++-----
>  arch/x86/kernel/kprobes/core.c |  2 +-
>  arch/x86/kernel/kprobes/opt.c  |  5 +----
>  3 files changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h
> index 5a6d287..9454c16 100644
> --- a/arch/x86/include/asm/kprobes.h
> +++ b/arch/x86/include/asm/kprobes.h
> @@ -49,10 +49,10 @@ typedef u8 kprobe_opcode_t;
>  #define flush_insn_slot(p)	do { } while (0)
>  
>  /* optinsn template addresses */
> -extern kprobe_opcode_t optprobe_template_entry;
> -extern kprobe_opcode_t optprobe_template_val;
> -extern kprobe_opcode_t optprobe_template_call;
> -extern kprobe_opcode_t optprobe_template_end;
> +extern __visible kprobe_opcode_t optprobe_template_entry;
> +extern __visible kprobe_opcode_t optprobe_template_val;
> +extern __visible kprobe_opcode_t optprobe_template_call;
> +extern __visible kprobe_opcode_t optprobe_template_end;
>  #define MAX_OPTIMIZED_LENGTH (MAX_INSN_SIZE + RELATIVE_ADDR_SIZE)
>  #define MAX_OPTINSN_SIZE 				\
>  	(((unsigned long)&optprobe_template_end -	\
> @@ -62,7 +62,7 @@ extern kprobe_opcode_t optprobe_template_end;
>  extern const int kretprobe_blacklist_size;
>  
>  void arch_remove_kprobe(struct kprobe *p);
> -void kretprobe_trampoline(void);
> +asmlinkage void kretprobe_trampoline(void);
>  
>  /* Architecture specific copy of original instruction*/
>  struct arch_specific_insn {
> diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
> index 211bce4..048852d 100644
> --- a/arch/x86/kernel/kprobes/core.c
> +++ b/arch/x86/kernel/kprobes/core.c
> @@ -661,7 +661,7 @@ static void __used __kprobes kretprobe_trampoline_holder(void)
>  /*
>   * Called from kretprobe_trampoline
>   */
> -static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
> +__visible __used __kprobes void *trampoline_handler(struct pt_regs *regs)
>  {
>  	struct kretprobe_instance *ri = NULL;
>  	struct hlist_head *head, empty_rp;
> diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
> index 76dc6f0..2c1ac28 100644
> --- a/arch/x86/kernel/kprobes/opt.c
> +++ b/arch/x86/kernel/kprobes/opt.c
> @@ -88,9 +88,7 @@ static void __kprobes synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long v
>  	*(unsigned long *)addr = val;
>  }
>  
> -static void __used __kprobes kprobes_optinsn_template_holder(void)
> -{
> -	asm volatile (
> +asm (
>  			".global optprobe_template_entry\n"
>  			"optprobe_template_entry:\n"
>  #ifdef CONFIG_X86_64
> @@ -129,7 +127,6 @@ static void __used __kprobes kprobes_optinsn_template_holder(void)
>  #endif
>  			".global optprobe_template_end\n"
>  			"optprobe_template_end:\n");
> -}
>  
>  #define TMPL_MOVE_IDX \
>  	((long)&optprobe_template_val - (long)&optprobe_template_entry)

-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com


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